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SQL
SQL Meaning
SQL (Structured Query Language)is a specialized programming language designed for managing and manipulating data stored in relational databases. It allows users to perform various operations such as querying, updating, inserting, and deleting data efficiently12.
Key Principles of SQL
Declarative Language: SQL is a declarative language, meaning it specifies what data to retrieve or manipulate rather than how to perform the operation. This makes it easier to use and understand1.
Standardization: SQL became a standard of the American National Standards Institute (ANSI) in 1986 and the International Organization for Standardization (ISO) in 19872.
Components: SQL consists of several sublanguages, including Data Query Language (DQL), Data Definition Language (DDL), Data Control Language (DCL), and Data Manipulation Language (DML)1.
Common SQL Commands
SELECT: Retrieves data from a database.
INSERT: Adds new records to a database.
UPDATE: Modifies existing records.
DELETE: Removes records from a database.
CREATE: Creates new database objects like tables and views.
ALTER: Modifies existing database objects.
Example of a Simple SQL Query
SELECT*FROMCustomersWHERECustomerNameLIKE'J%'ORDER BYCustomerIDDESCLIMIT 10;
This query retrieves the top 10 customers whose names start with 'J', ordered in descending order by their customer ID3.
Uses of SQL
SQL is widely used across various industries and applications, including:
Data Retrieval: Extracting data from databases for analysis and reporting.
Data Manipulation: Adding, updating, and deleting data in databases.
Data Definition: Defining the structure and organization of data in databases.
Access Control: Managing user permissions and ensuring data security23.
Important Considerations
Interoperability: SQL implementations can vary between different database systems, leading to compatibility issues1.
Security: SQL injection is a common security vulnerability where malicious SQL code is inserted into queries to manipulate or corrupt data3.
In conclusion, SQL is a powerful and versatile language for managing relational databases, offering a wide range of functionalities for data manipulation, retrieval, and security12.
Glossop is a market town in the High Peak, Derbyshire, England, 12 miles (19 km) east of Manchester, 24 miles (39 km) northwest of Sheffield and 32 miles (51 km) north of the county town, Matlock, near Derbyshire's borders with Cheshire, Greater Manchester, South Yorkshire and West Yorkshire. It is between 150 and 300 metres (492 and 984 ft) above mean sea level, and lies just outside the Peak District National Park.
Historically, the name Glossop refers to the small hamlet that gave its name to an ancient parish recorded in the Domesday Book of 1086, and then the manor given by William I of England to William Peverel. A municipal borough was created in 1866, and the unparished urban area within two local government wards.[1] The area now known as Glossop approximates to the villages that used to be called Glossopdale, on the lands of the Duke of Norfolk. Originally a centre of wool processing, Glossop rapidly expanded in the late 18th century when it specialised in the production and printing of calico, a coarse cotton, and became a mill town with many chapels and churches, its fortunes tied to the cotton industry.
Architecturally, the area is dominated by buildings constructed of the local sandstone. There remain two significant former cotton mills and the Dinting railway viaduct. Glossop has transport links to Manchester, making the area popular for commuters.
